Insulin-like growth factor-I and environmental modulation of growth during smoltification of spring chinook salmon (Oncorhynchus tshawystscha).
The relations among rearing environment, fish size, insulin-like growth factor-I, and smoltification were examined in yearling spring chinook salmon (Oncorhynchus tshawytscha). Juvenile chinook salmon were size-graded into small and large categories. Half of the fish in each group were reared at an increased temperature and feeding rate beginning in mid-February, resulting in four distinct treatment groups: large warm-water (LW), large cool-water (LC), small warm-water (SW), and small cool-water (SC). Increased temperature and feeding rate resulted in overall higher growth rates for the LW and SW groups. Temporal increases in insulin-like growth factor-I (IGF-I) were found in all groups through the spring. Plasma IGF-I levels were significantly higher in warm-water groups than in cool-water groups from late March through May. Size itself appeared to have little relation to plasma IGF-I levels. Simple regression showed a significant relation between plasma IGF-I and growth (P < 0. 001, R2 = 0.50). No differences were found between treatment groups in other physiological parameters assessed (plasma thyroxine, gill Na+-K+-ATPase, liver glycogen, body lipid).
Beckman
B R
BR
Northwest Fisheries Science Center, National Marine Fisheries Service, Seattle, Washington, 98112, USA. beckman@fish.washington.edu
Larsen
D A
DA
Moriyama
S
S
Lee-Pawlak
B
B
Dickhoff
W W
WW
D000818:Animals; D001824:Body Constitution / Q000502:physiology; D005880:Gills / Q000201:enzymology; D006003:Glycogen / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000502:physiology*; D008055:Lipids / Q000097:blood; D008099:Liver / Q000378:metabolism; D012474:Salmon / Q000254:growth & development* / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013696:Temperature; D013974:Thyroxine / Q000097:blood
D008055:Lipids; D007334:Insulin-Like Growth Factor I; D006003:Glycogen; D000254:Sodium-Potassium-Exchanging ATPase; D013974:Thyroxine